1. Field of the Invention
The present invention relates to an acrylic film useful as a substrate of a lens film. The invention also relates to a lens film comprising the acrylic film as a substrate and further relates to a lens sheet obtained by laminating the lens film on a resin sheet.
2. Description of the Related Art
A transmission-type screen, which can be used in a projection-type television, a micro reader and the like, generally comprises a lens sheet such as Fresnel lens sheet and Lenticular lens sheet. Such a lens sheet can be produced by forming a lens layer of ultraviolet-setting type resin on a film substrate to obtain a lens film, and then laminating the lens film onto a resin sheet as a support. Thus-obtained lens sheet is advantageous in terms of fine pitch adjustment and productivity.
The lens film is known, for example, in Japanese Patent Application Laid-Open No.11-262958 such that a lens film is produced using a polyester or polycarbonate film as a substrate. The conventional lens film, however, may have insufficient light fastness, which may result in change in color, and may be easily warped or sagged depending on the environmental fluctuation when the lens film is laminated on a resin sheet.